1. Field of the Invention
The present invention relates to a diode array for use with solid state lasers and more particularly to a diode array which includes one or more diode bars, each diode bar including a one-dimensional array of laser diodes, disposed along one edge of a carrier; the laser diodes being configured to emit light parallel to an optical axis. The diode bars are sandwiched by contiguous spacer layers. Multiple spacers are provided per layer. The spacers in each layer are configured such that the gaps between the spacers are formed at non-parallel angles relative to the optical axis in order to average out any adverse affects of the gaps to provide increased uniformity of the optical outputs of the diodes forming the diode bars.
2. Description of the Prior Art
Diode arrays are known to be used with solid state lasers. In particular, such solid state lasers are known to include an optical amplifier, formed from a slab of lasing material, such as yttrium-aluminum-garnet (YAG) crystal. The diode arrays are used to excite the atoms within the lasing material to a relatively high metastable state to cause lasing action. Examples of such solid state lasers which utilize diode arrays for pumping are disclosed in U.S. Pat. Nos. 4,852,109 and 5,555,254, hereby incorporated by reference.
In order to improve the performance of the laser, light energy from the diode arrays must be relatively uniform along a direction orthogonal to the laser's optic axis to reduce thermal and stress aberrations of the resulting laser beam. Such aberrations of the resulting laser beam are known to be caused from several sources. More particularly, as discussed in detail in commonly owned copending patent application Ser. No. 08/766,434, filed on Dec. 12, 1996, in many known applications, the diode arrays are mounted one on top of another. With such a configuration, there is a non-uniform deposition of energy in the vertical direction of the lasing material resulting in unpumped zones in the lasing material which causes aberrations in the resulting laser beam. In particular, pumping of the atoms within the lasing material produces considerable heat in the areas where the atoms of the lasing material are pumped. Since the materials used for many known lasing materials are relatively poor thermal conductors, the unpumped zones cause thermal gradients in the lasing material across the laser beam, resulting in stress and thermal aberrations of the resulting laser beam. The above-mentioned copending application solves this problem by providing a plurality of diode arrays, configured to provide generally uniform energy distribution in the lasing material across the laser beam.
Another cause of aberrations in the resulting laser beam from a solid state laser is from the non-uniform light output from the laser diodes forming the diode array. More particularly, such diode arrays are known to include a plurality of laser diodes aligned along one edge of a substrate or a carrier and configured such that the light output from each of the laser diodes is parallel to an optical axis, generally perpendicular to the edge along which the laser diodes are disposed. The diode bars are generally sandwiched between layers of spacers, as generally discussed in U.S. Pat. Nos. 4,454,602 and 4,716,568, hereby incorporated by reference. More particularly, a portion of a conventional diode array is illustrated in FIG. 1 and generally identified with the reference numeral 20. As shown, the diode array 20 includes a diode bar 22 which includes a plurality of laser diodes 24, configured such that their light output is generally parallel to an optical axis indicated by the arrow 26. The diode arrays 20, are known to be formed in a stacked relationship with a plurality of diode bars 22 and attached to a heat sink for dissipating heat created by the laser diodes. In order to separate the diode bars 22, spacers, such as the spacers 28 are used. Conventional diode arrays are known to include multiple segmented spacers 28 per layer, for example, as illustrated in FIG. 1, which have gaps 30 and 32; the gaps being generally parallel to the optical axis 26. These gaps 30 and 32 can cause electrical, thermal or mechanical non-uniformities of the mounting of the diode bars 22 relative to the spacers. These non-uniformities can result in variations in the output from the various laser diode emitters forming the diode bar 22. Variations of the output of the various laser diodes can degrade the overall performance of the overall diode array and thus the resulting laser beam from the solid state laser. Thus, there is a need to provide a diode array in which the output from the individual laser diodes forming a diode bar is relatively uniform.